We will pay for this [climate change] one way or another. We will pay to reduce greenhouse-gas emissions today and we'll have to take an enormous hit of some kind. Or we will pay the price later in military terms. And that will involve human lives. There will be a human toll. There is no way out of this that does not have real costs attached to it.

I think the Mogadishu effect, if I had to define it, is we need to be more careful where we decide to commit US forces, and for what reason, and to make a clear judgment as to what we can and can't do and whether it's in our interests, or we could afford the resources that it would take to make the situation right.

You have to give everybody another recourse as some means other than violence, no matter how distasteful it may be to have to deal with them and what they represent.

I think that before you take on nation building in your mind's eye as to how it should be, you'd better have a clear understanding if this is doable and will work.

We will pay for this [climate change] one way or another. We will pay to reduce greenhouse-gas emissions today and we'll have to take an enormous hit of some kind. Or we will pay the price later in military terms. And that will involve human lives. There will be a human toll. There is no way out of this that does not have real costs attached to it.

If you put two brigades on the ground right now with U.S. forces, they would push ISIS back into Syria in a heartbeat.

In the lead-up to the Iraq war and its later conduct, I saw, at a minimum, true dereliction, negligence, and irresponsibility; at worst, lying, incompetence, and corruption.